光磁盘存贮

本文从光磁记录和读出的原理出发,讨论了记录介质材料的要求和提高信噪比的方法。同时,对记录和读出装置的关键部件——光学头——进行了分析与研究。本文还提出了光磁盘的主要测试参数和要求。     

数字录像机格式概述

数字录像机和模拟录像机相比,具有信噪比高、清晰度高、记录密度高、误码纠错功能好,多版复制功能好,各种设备之间的数字连接简单,便于和非线性编辑系统配套组成节目后期制作系统等优点。但其格式多样而且互不兼容。对于数字信号,一般来说不会由于记录和重放,以及信号处理而引进噪波干扰,因而能保持很高的信噪比。在相同的信噪比下,记录数字信号的磁迹宽度比模拟信号的记录磁迹窄得多,因此,数字记录有利于提高图像的记录密度。数字录像信号中采用了前向误码纠错的方法,如果由于某种原因发生信息丢失,在一定程度上能够自动进行校正,在重放图…     

纳米晶巨磁光BiAlDyIG薄膜的磁光性能研究

基于对ＢｉＡｌＤｙＩＧ巨磁光材料的紫蓝光波段法拉第角频谱分析，采用新型热分解法工艺合成优质ＢｉＡｌＤｙＩＧ磁光薄膜，经快速循环晶化处理的结果表明，由于晶粒细化，其平均有效法拉第角比常规热处理后的样品大０．５°左右，且随循环数增加而增大。同时由于Ａｌ３＋在四面体和八面体位的取代，导致居里温度下降（１４０～１６０℃），这些结果对提高磁光盘信噪比以及增大记录密度是极有意义的     

基于小波变换域上的KL变换的地震信号去噪方法

基于相邻地震道的有效波在波形及能量上有较强的相关性及改变各个频率成分的信噪比．有益于提高分辨率的观点，本文提出了基于小波变换域上的KL变换去噪方法．该方法的主要思想是：将地震记录进行小波分解，形成地震记录的分时、分频小波包剖面，然后利用相邻道相关的性质，用KL变换进行去噪，再将各个小波包剖面重构为去噪后的地震剖面．理论记录计算及实际地震剖面的处理结果表明：基于小波变换的分时、分频KL变换去噪方法能有效地提高地震剖面的信噪比和分辨率．     

通信设备及其他

静止磁盘、动态磁头的“录放装置”查询号２５０随着磁性记录技术的发展，一种构造新颖的录放装置专利技术由海拉尔力普机械电子研究所北京分所推出。利用该技术制造的录放装置与现有录放装置结构不同，它采用静止的磁盘（片）做记录载体，其表面贴放的磁头按不同半径做螺旋状旋转运动，以动态方式在磁盘（片）的磁道上寻迹，配合录放电路实现录放功能。采用这一技术可开发多种实用产品，如有声儿童读物、盲文辅助学习器、电子信件、产品有声说明书、环形码记录与读出装置等。其中有声儿童读物的使用方法是在每张画面的适当位置涂敷一层磁浆…     

磁光记录及其介质

磁光记录作为可擦除式光盘存储是当前最有吸引力的光存储技术.它具有光盘存储容量大的特点,又有磁记录随录随取的优点.另外,提高磁盘的记录密度,必须减小磁头的尺寸,降低磁头和盘面的间距和减薄介质的厚度,这在技术上遇到了相当大的困难.但是,光存储技术是非接触式的,作为录放头的半导体激光器又极易聚焦,它不仅克服了技术上的难点,又提高     

索尼公司将推出新一代音响产品——磁光唱机

近几年来,激光唱机(CD)以其容量大,保真度高的特点,受到广大音乐爱好者的青睐。正当激光唱机风靡世界之际,日本索尼公司却不惜耗费巨资,加紧研制新一代的音响产品——磁光唱机(MD),预计不久将推向市场。与激光唱机相比,这种磁光唱机的最大特点是可实现任意抹音和重录,它是通过不同的磁场排列来记录音乐信号,再用激光来扫描发送载录在磁盘上的音乐信号;抹音时,利用激光将磁盘上的关键性材料加热磁化,消除原有信号。这种磁光唱机不受磁     

提高铁氧体环行器峰功率容量的概述

本文概述提高铁氧体环行器峰功率容量的方法：一是从铁氧体材料工艺考虑，采用规一化饱和磁矩较低而自旋波线宽圈大的材料，二是从外加磁化场考虑，将铁氧体材料偏磁于低场区，次高场区或高场区，以抑制自旋波的不稳定激发。     

光磁盘存贮技术与装置

对光存贮概念的研究,最早始于美国。1957年贝尔实验室Williams用热笔对MnBi薄膜进行记录。由此至今,美日等国为制成这种存贮装置,进行了二十多年艰苦曲折的探索。随着非晶质光磁存贮材料GdCo膜在1973年诞生,及最近以光盘发展为中心的半导体激光器技术和激光束精密控制伺服技术的进展,从80年代开始了研制光磁存贮器的新时期。当今,基于光磁存贮原理而正处于开发热潮之中的光磁盘,实际就是用磁性薄膜作记录介质,以激光束来记录、再现和清除信息的一种磁盘。它既有光存贮记录密度高的特点,也有可清除信息进行重写的功能。利用它极有希望制成大容量     

纳米磁性材料

纳米颗粒为单磁畴结构，其磁化过程属旋转磁化。纳米材料可作永磁材料，其矫顽力很高，用作磁记录时可提高信噪比，改善图象质量。     

采用不同中间夹层的双记录层磁光光盘热光特性比较

磁光存储技术是一种颇受关注的下一代光存储技术.为提高单个磁光光盘的存储容量,途径之一是采用多值存储、多波长读出技术,实现所谓三维磁光存储.通常使用不同波长的蓝光来实现信号的读写操作.如果不同波长的激光在磁光存储多层膜中产生热场分布的差异较大,将有利于提高读出信号的信噪比.本文结合光学矩阵法及有限元方法分析了中间夹层分别为SiN、GaP时,磁光存储多层膜的热光特性.结果表明在蓝光波段,用GaP层替代传统的SiN中间夹层,将使磁光光盘具有更好的热光特性.     

基于卡尔曼滤波的锁相环算法研究

在某卫星载荷—感应式磁力仪的设计中,需要提取高动态环境下的磁场信号并降低所获信号的噪声干扰。基于此提出了一种改进的基于卡尔曼滤波的锁相环设计算法并应用于感应式磁力仪数据处理单元DSP的软件设计中,设计采用扩展卡尔曼滤波方法结合传统全数字软件锁相环的方法对待测信号进行滤噪、跟踪,获取信号的频率信息并通过锁相放大器获取信号的幅值、相位信息,并进行了仿真和实验验证。实验结果表明,改进的锁相环可以有效的对多普勒频率变化率为f=500Hz/s,信噪比低至-20dB的信号进行跟踪。该方法已应用于感应式磁力仪地面设备的信号检测和提取。     

A 160-MHz analog equalizer for magnetic disk read channels

This paper presents a 160-MHz five-tap adaptive analog equalizer for magnetic recording disk drive read channels. The design is based on a direct form finite impulse response (FIR) architecture which includes four key features: signal shuffling in the analog domain to improve noise performance, use of a master sample-and-hold stage to improve the dynamic performance and clock jitter of the clock recovery loop, use of an additional sample-and-hold stage to accommodate settling time requirements and reduce power, and use of a time interleaved sign-sign LMS algorithm which permits coefficient adaptation at low power and area. This equalizer occupies 1.36 mm² and consumes only 240 mW with 5-V supply voltage. It is fabricated in BiCMOS technology with 0.8-μm CMOS and 0.72-μm² NPN, 3LM, and DP capacitor     

Digital video recording

Through mutual technology transfer between consumer and professional video recorders, the last 20 years has witnessed a rapid evolution from analog to digital recording. Each new digital videotape recorder (VTR) uses different channel coding. This implies that improving the recording density involves the development of new channel-coding schemes together with evolutionary magnetic tapes and heads. As a result, professional digital VTR's offer the best features for video recording. This paper reviews state-of-the-art magnetic recording devices, signal processing techniques for digital recording. It also describes the specifications for home-use digital recorders for current television systems, and discusses disk recording technology in the future     

磁盘记录信号的热磁衰减现象的记录密度依赖性

超大容量的外存储设备在计算机网络日新月异的发展过程中变得越来越重要.而存储容量的增加势必带来由于热衰减现象引起的记录信号衰减的问题.本文通过计算机仿真与实验,研究了磁盘介质中记录信号的热磁衰减现象.文中着重讨论了信号的热磁衰减对记录密度的依赖性,同时考虑了介质参数对衰减量的影响.指出垂直磁记录方式是超高密度记录的最适宜方式之一.     

1/2-inch cassette VTR for baseband HDTV signal recording

Technical details are reported for a 1/2-inch cassette videotape recorder (VTR) developed for recording the baseband high-definition TV (HDTV) signal. A recording time of 63 min was achieved by using metal-particle tape and laminated amorphous video heads. The frequency bandwidths used for luminance and chrominance signals were 20 and 7 MHz, respectively. A novel two-channel, three-segment recording method was developed for the purpose. Four-channel digital audio recording with a sampling frequency of 48 kHz and 16-b linear quantization was used. The digital audio signal was recorded on the overlapped area succeeding to the video track by using the same heads used for video recording     

Magnetic recording systems

This review of magnetic recording systems concentrates on developments in two particular areas: the video-tape recorder and the rigid disk drive. The consumer VCR represents the state of the art for analog in-contact recording, while the rigid disk drive exemplifies digital recording with rapid access. Various aspects of the mechanical configurations, track-following techniques, heads and media, and signal processing are discussed. More briefly the paper describes other digital systems on flexible media.     

Magnetooptics: A thermomagnetic recording technology

Erasable magnetooptic (MO) recording is viewed as a possible successor to electromagnetic recording that is used today in high-performance disk drives for mainframe computers, hard disks, and floppy disks for personal computers and magnetic tape drives. A large number of rare earth-transition metal alloys have been investigated for use as the magnetic recording material. The properties of the films are very sensitive to the film deposition processing parameters. Accelerated life tests show that there are magnetooptic materials that do have all of the necessary properties and stability for use in computer digital storage.     

未来数据储存技术与硬盘的发展

走过了半个世纪的磁储存技术,小型化牵动着数据储存和计算机硬盘到达了从未有过的高度。正在研究发展的热辅助记录技术和图形媒介技术将会给磁记录硬盘带来更高的面密度,从而使小型化在磁储存的框架内还将有一段路可走。但由于其物理限制,磁硬盘无法永远继续小下去,人们正在寻找新的出路。因此除了对磁储存正在发展的两项新技术之外,特别是对完全另辟新路的非磁数据储存技术,如纳米机械AFM数据储存技术、全息光储存技术以及原子储存技术进行了论述,以显示当前该领域前沿科技的发展概貌。     

Self-timed dynamically pipelined adaptive signal processing system: a case study of DLMS equalizer for read channel

Many pipelined adaptive signal processing systems are subject to a tradeoff between throughput and signal processing performance incurred by the pipelined adaptation feedback loops. In the conventional synchronous design regime, such throughput/performance tradeoff is typically fixed since the pipeline depth is usually determined in the design phase and remains unchanged in the run time. Nevertheless, in many real-life scenarios, the overall system performance can be potentially improved if we can run-time dynamically configure this tradeoff. With this motivation, we propose to apply self-timed pipeline, an alternative to synchronous pipeline, to implement the pipelined adaptive signal processing systems, in which the pipeline depth can be dynamically changed to realize run-time configurable throughput/performance tradeoffs. Based on a well-known high speed self-timed pipeline style, we developed architecture and circuit level design techniques to implement the self-timed pipelined adaptation feedback loop with configurable pipeline depth. We demonstrate the proposed design approach using a delayed least mean square (DLMS) adaptive equalizer for magnetic recording read channel. The data transfer rate in hard disk varies as the read head moves among tracks with different distance from the center of the disk platter. By adjusting the pipeline depth on-the-fly, the DLMS equalizer can dynamically track the best equalization performance allowed by the varying data transfer rates. Simulation result shows a significant performance improvement compared with its synchronous counterpart.